These teachings relate generally to lasers, and, more particularly, to laser systems operating at two or more wavelengths.
Traditional laser tools for cutting biological soft tissue comprise lasers radiating around 1 microns, including laser diodes based on InGaAs semiconductor. At the same time, traditional laser tools for ablating biological hard tissue comprise lasers radiating in the wavelength range of 2.5-3 microns or around 10 microns. In many instances the surgeon, medical practitioner or dentist requires the application of both laser types for a smooth and easy transition between various tissues and convenience for the patient.
Previous laser tools have generally been separated into applications for the soft and hard tissue. A laser apparatus for removing only dental enamel and dentin, pumped by unspecified means, has been previously disclosed. The practical application of a laser at 2.5-3 microns requires the use of specialized fibers, for instance Germanium-oxide or Fluorozirconate or fluoride glass fibers, for the purpose of beam delivery to the target. Diode pumped laser of this category have been previously disclosed. An efficient delivery of 2.5-3 microns radiation in each of the above disclosures over distances of a meter or a few meters can be accomplished only by employing such specialized fibers as aforementioned that have the characteristics of brittleness, water solubility, toxicity, sensitivity to UV exposure, limited mechanical strength, low temperature damage threshold and low laser damage threshold.
The capability of emitting and delivering two laser wavelengths, one that of the diode pump and the other at 2.94 microns, has been previously disclosed for an ophthalmic surgical laser featuring parameters specifically applicable to that use.
Regarding lasing media of interest, a laser gain medium comprising undoped and doped host materials bonded to one another has been previously disclosed wherein the doping is by laser active rare-earth ions so that thermal lensing in reduced.
A solid-state laser placed in a hand-held surgical probe connected to the pump laser diode by a fiber bundle has been previously disclosed where the laser is limited to low energy per pulse ˜<10 mJ, low pulse repetition rate ˜20 Hz. This limits the practical use of that device to ophthalmic applications and not for hard tissue ablation.
Also regarding gain media, thin slab laser crystals in which the laser beam propagates at a shallow, grazing angle relative to one of the slab long sides have been previously described. A composite slab where the doped, sub-millimeter laser active crystal is diffusion bonded to an undoped cap made of the same host material has also been previously described. Previous disclosures are related to Nd based lasers.
There is therefore a need for a handheld surgical laser system which is suited to cut soft biological tissues and ablate hard biological tissues.